Who could have dreamed up the strange political scenario that brought us the Carter-Teng show on Washington TV over the past few days? The reborn Christian peanut farmer from Georgia is showering hospitality and diplomatic favor on the politically twice reborn revolutionary soldier and bureaucrat from Asia. Their public embrace is clearly designed to bolster their respective political images, in both cases at some cost to previous assertions of principle and, hence, at considerable risk of providing ammunition to domestic opponents. Why?. Why now? And what will follow?

Teng Hsiao-ping's motives are clear, and he is setting the predominately anti-Soviet tone of the encounter. The mystery is why Jimmy Carter is going along. Teng is gambling that he can consolidate his own domestic political power base and protect China from the Soviet Union by fashioning a temporary, informal alliance with the United States, borrowing billions of dollars from capitalist states and importing modern technology for China's industry, agriculture, and military forces.

Teng has battled for his life and for power ever since he joined the Communist Party as a teen-age student in France in the early 1920s. He is 74 years old, and this is his last chance to confound his opponents in the party and the army. Since Teng was purged in 1966 precisely for "taking the capitalist road," his new maneuver of turning to the United States is consistent enough but extremely daring. His enemies of the past 15 years and more are still in high posts; if Teng does not bring home the bacon in the form of strong anti-Soviet security assurances from Washington, plenty of long-term credit and modern weapons, he may encounter increasing resistance from his political antagonists.

Obviously, President Carter, National Security Adviser Zbigniew Brzezinski and the State Department have led Teng to believe they are ready to give him almost whatever he wants. They were so anxious to get him to promise to come to Washington when their touted Israeli-Egyptian accords were coming unstuck that they hastily derecognized the Republic of China and terminated a mutual defense treaty with the island. Five American presidents had refused to treat this longtime, faithful American ally so shabbily, capitulating to all of Peking's conditions for recognition and abandoning all of our earlier commitments to the 18 million Chinese on Taiwan.

Naturally, Teng comes to Washington with whetted appetite and high hopes. It is too much to expect him to understand that Brzezinski's blithe geopolitical challenges to the Soviet Union of the kind voiced at the Great Wall last summer are not a commitment to military confrontation of the kind Teng says he expects. Nor would he foresee that there would be congressional and popular resistance to Carter's secret agreement to treat Taiwan as a non-nation, having only "unofficial" relations with the United States. In the People's Republic of China, legislative and popular influence is not a political factor in the decision-making, but it still has some meaning in Washington.

It is far from certain whether Carter can really give Teng what he wants, both total control over the ultimate fate of Taiwan and a vast Western economic and military-aid program in direct defiance of the Soviet Union. Probably Carter does not relish wrecking his "human-rights" ideology by rendering Taiwan vulnerable to a political takeover, whether by guile or force, and he surely did not reckon on a major strategic confrontation with Leonid Brezhnev over China.

Moscow has already given Vietnam the green light to humiliate Communist China by an outright military conquest of Cambodia, in effect challenging Peking and Washington to do something about it. Fighting may continue on both China's borders, north and south, if Moscow stays fearful that Teng will euchre Carter into a real Peking-Washington axis. Unless Jimmy Carter is careful, he will end up facing a land war in Asia that would put America on the side of a pitifully weak People's Republic of China against the most powerful military machine in the world -- the Soviet Union. This could not have been where Carter thought he was going when he made his hasty deal with the crafty Chinese leader. It is certainly not where most Americans want to go.

The president has a chance to set limits to P.R.C. hopes and restore American credibility and international respectability if he acquiesces in the strong congressional trend to put American relations with Taiwan back on an official and legal basis rather than proceeding at Teng's insistence to treat the Republic of China not as a sovereign nation controlling Taiwan, but as a subordinate part of the P.R.C.

Probably not much can be done to dampen Teng's inflammatory rhetoric about meeting the danger of war with the Soviet Union. On the other hand, Congress may wisely refuse to go along with the president's proposed bill to manage the foreign relations and security arrangements with Taiwan through a "private corporation," thus saving Carter from his own folly of having given in to the Peking's every demand -- something that startled Moscow along with nearly everyone else. This congressional act would signal to the importunate People's Republic that it has won diplomatic recognition from Washington, not dominance over American foreign policy in its relations with either its allies, such as Taiwan, or its great adversary, the U.S.S.R. The Carter-Teng show might not be such a hit as hoped by the White House, but the world would be a little saner and safer.